I don't think the Kalpoes were on the beach with Joran and Natalee either. Joran is a big greedy lustful lout, and I just cannot picture him sharing any of his conquests with the Kalpoe boys, whom Anita VDS was careful to point out...are not REALLY Joran's best friends...more on the outer fringes. She is a nasty piece of work.
The remnants of the old colonial class system are still alive and well on Aruba, so the Kalpoe brothers are way down on the social scale and not likely to be invited to any VDS dinner parties. I really liked Mrs. Kalpoe, however. In her interview with Greta, she was sincere, simple, heartbroken, worried, and trying to keep her life together and her sons back. Mrs. VDS is busy blaming everybody else but Joran and Paulus at this point.